Preprocessor



Sept. 29, 1970 R. E. PRENTICE PREPRO CES SOR 2 Sheets-Sheet 1 -FiledApril 11. 1968 Russell E.Prenfice,

INVENTOR GOLOVE a KLEINBERG ATTORNEYS.

R. E. PRENTICE PREPROCESSOR Sept. 29, 1970 2 Sheets-Sheet 2 Filed April11. 1968 Utili zoiion Device Russell Ej'Prenric INVENTOR.

GOLOVE & KLYEINBERG,

ATTORNEYS.

United States Patent Int. Cl. G03b U.S. Cl. 355-133 4 Claims ABSTRACT OFTHE DISCLOSURE Apparatus cleans positive and negative film stock priorto being placed into intimate surface contact utilizing pairs of opposedradioactive ionizers and opposed brushes which intercept the positiveand negative film for removing contaminants from the film surfaces. Thepositive film, where appropriate also pass over a preexposer, whichcontrollably preexposes the raw positive prior to a contact printingstep. A high capacity vacuum line pulls a large volume of air at highvelocity across the film surfaces, transverse to the direction of filmtravel, to sweep surface contaminants from the vicinity of the film, tocontinuously agitate the brushes to prevent the retention ofcontaminants and to cool the preexposer light source.

The present invention relates to film processing devices and moreparticularly to apparatus for cleaning developed negative, and rawpositive film stock, prior to their combination for use in a contactprinter and, in the case of positive film which should be preexposed forheightened sensitivity, for selectively preexposing such raw film stock,prior to the combination with the negative film.

It has long been known that it is desirable, prior to bringing negativefilm and raw positive stock into intimate surface contact and beforeapplication to a contact printer, for both films to be thoroughlycleaned of all surface contaminants. Since, in contact printingapplications it is imperative that the negative and positive film be inas intimate contact as is possible, any particulate matter, which couldeither scratch or deform the film while being processed, or which wouldresult in a local separation between the positive and negative films,should be removed from the immediate environment.

It is known that the phenomenon of static electricity can and doesprovide substantial forces of mutual repulsion which tend to repelsurface contaminants, and accordingly, radioactive ionizers are used forfilm cleaning. It is also known, in connection with certain types ofpositive film stock, such as that which is sold under the trademarkKalvar and which is produced by the Kalvar Company of New Orleans, La.,that some uniform, limited preexposure of the raw stock, before theprinting step is undertaken, increases the sensitivity of the film.While the exact explanation of this phenomena is not known, it isbelieved that a certain hysteresis or inertia may exist in the responseof the positive emulsion to actinic radiation. The preexposure steptends to provide energy to the emulsion, which, although insufiicient tocause noticeable exposure, reduces the quantum of additional radiationnecessary to provide a good quality print.

Prior art devices have been available to apply an electrostatic chargeto the film surface. Other devices are available to clean particulatematter from the surface of the film. An air squeegee is available thatwipes the surface of the film with a flow of air directed at thesurface. In those applicatitons where preexposure of the positive filmis desirable, simple preexposers can be provided. However, there hasbeen a need for a single device which can effectively perform all ofthese functions and, after the positive and negative films are cleaned,charged and the positive preexposed, immediately bring the positive andnegative films into intimate contact for subsequent application to acontact printer or other utilization device.

According to the present invention, a high volume flow of coolant, suchas air, is provided, across the surface, transverse to the direction offilm travel, to remove any contaminating matter from the vicinity.Radioactive ionizers and brushes are provided to remove contaminantsfrom the film surface. The high velocity, high volume air flow alsovibrates the brushes to clean them of any matter accumulated therein.Further, the air flow can be utilized to cool the light source which isnecessary for the preexposure step.

In a preferred embodiment, a negative film path and a positive film pathare provided through a preprocessing unit. Interposed in both film pathsat a first station are radioactive polonium ionizing elements whichimpart an electrostatic charge to the film surfaces. At a secondstation, opposed brushes contact both surfaces of the film to sweep" anyremaining contaminants from the film surfaces. A third station isprovided in the path of the positive film, at which station a preexposeris placed. The preexposer has an adjustable exposure slit so that anappropriate amount of actinic radiation can impinge upon the raw stock,relative to the rate of film travel.

A protective housing partially encloses the film path and stations, butis open to the surrounding environment along the line of film travel.The back of the apparatus is substantially open and is coupled into avacuum system capable of handling a high volume of air at relativelyhigh velocities, assuming the environment is at normal atmosphericpressure.

In specialized applications, it may be desirable to maintain the film inan inert gaseous environment under which circumstances either the vacuumconnection is made, or, the back of the apparatus is connected to asource of fluid under pressure, so that a high velocity fluid flow in adirection transverse to the direction of film travel is available. Byuse of the term fluid both liquids and gases are intended, and, inappropriate applications, either may be employed. In embodiments whereinthe preexposer is included, the fluid flow path includes the radiationsource for cooling purposes.

While the preferred embodiment of the present invention is intended foruse in conjunction with high speed continuous contact printers for film,it is clear that the present invention could be adapted for any highspeed winding and reeling systems in which the surfaces of one or morewebs must be subjected to a cleaning step to remove surfacecontamination.

The simultaneous application of a high-volume fluid flow in a directiontransverse to Web travel, with a brush station and/or a static-chargingstation, tends to sweep surface contaminants out of the area of webtravel. The high volume fluid flow also agitates the brushes to keepthem free of contaminants, and to release any contaminants that might beentrapped by the bristles thereof.

The novel features which are believed to be characteristic of theinvention, both as to organization and method of operation, togetherwith further objects and advantages thereof will be better understoodfrom the following description considered in connection with theaccompanying drawings in which several preferred embodiments of theinvention are illustrated by way of example. It is to be expresslyunderstood, however, that the drawings are for the purpose ofillustration and description only and are not intended as a definitionof the limits of the invention.

FIG. 1 is a perspective view of preprocessing apparatus according to thepresent invention, in which unexposed 3 positive film stock traversesthe upper path and negative film traverses the lower path;

FIG. 2 is a side view of the apparatus of FIG. 1 with the protectiveshroud removed; 7

FIG. 3 is a side sectional view of a preexposer unit useful in thepresent invention; and

FIG. 4 is a top view of a section of the apparatus of FIG. 2 taken alongline 4-4 in the direction of the appended arrow.

Turning first to FIG. 1, there is shown in perspective, a preprocessorfor film, according to the present invention. As shown, raw positivefilm 12 is inserted through a first opening 14 in the shroud 16 of theprocessor 10 and negative film 18 is applied through a second opening 20in the shroud 16. While not a part of the present invention, it may benoted, that the positive and negative film stock 12, 18 come fromseparate supply sources (not shown) and, upon their exit from thepreprocessor 10, are applied to an idler 22, at which point they arecombined in intimate surface-to-surface contact for subsequentapplication to a contact printer (not shown) or other utilizationdevice.

It is contemplated that the preprocessor 10 and the associatedprocessing apparatus (not shown) will be located in a relatively normalatmospheric environment at normal temperatures and pressures. However,for certain premium applications it may be desirable to house all theequipment in a dust-free, clean environment, where humidity, temperatureand pressure are carefully controlled.

In such an application, the preprocessor 10, as shown in FIG. 1, can beconnected either to a source of relatively low pressure, such as avacuum line (not shown), or, it can be connected to a source of highpressure (not shown). In either eventuality, the fluid flow path will besubstantially the same and only the direction of flow will be affected.In the preferred embodiment of FIG. 1, a connection is made to a highvolume, vacuum line and the direction of air flow is into the drawing.

A preexposure control knob 24 is provided which manually controls anexposure aperture of the preexposure unit, to be explained in greaterdetail in connection with the figures below. Only partially seen in FIG.1, are radioactive ionizers 26 for applying an electrostatic charge tothe film surfaces, and opposed brush pairs 28, for physically sweepingcontaminants from the surface of the film. These are described ingreater detail in connection with FIGS. 2 and 4, below.

Turning next to FIG. 2, there is shown a side view of the preprocessor10, with the front of the shroud 16 removed. The raw positive film 12passes through the opening 14 and, at a first station, betweenradioactive ionizing units 26 which are commercially available and whichutilize a radioactive source, such as polonium, to create a staticelectrical charge on the surface of the film 12. The creation of such astatic charge induces mutually repelling forces in the film and in anycontaminants that may be on the film. Such contaminants, when releasedfrom the film surface, are swept across the film by the high velocityair which traverses the film path. With respect to FIG. 2, the path ofair travel would be perpendicular to the plane of the drawing.

The air flow in the preferred embodiment is effected by the use of alarge chamber or plenum 17 which is connected to the vacuum source. Theopenings 14, 20 in the shroud 12 extend in the direction of the filmpath and communicate with the environment.

With the vacuum system operating, a low pressure exists in the plenum17, and the gradient to exterior, atmospheric pressure creates an airflow through the openings 14, 20 across the films 12, 18 and into theplenum 17.

In alternative embodiments, the back of the preprocessor 10 could befitted with a modified plenum, adapted to supply air under greater thanatmospheric pressure which would flow out of the openings 14, 20.

The film 12 continues between a pair of opposed brushes 28 which scrubthe film surface for any contaminants not released by the static charge.The high velocity air flow maintains the bristles 30 of the brushes 28in a state of constant agitation, thereby preventing the entrapment ofany contaminant particles in the bristles 30.

The path of the positive film 12 then traverses a third station whichincludes a preexposure drum 32, described in greater detail inconnection with FIG. 3 below. The drum 32 is connected to thepreexposure control knob 24 of FIG. 1, and includes a radiation source34, in the preferred embodiment an ultraviolet lamp, an inner aperturedcylinder 36 and an outer apertured cylinder 38. The inner and outercylinders are concentrically arranged and are rotatable relative to eachother.

As shown, the outer drum 38 is relative the preprocessor 10 and hasfixed a wide aperture 40 provided therein. The aperture may subtend anarc of approximately 45 to 60 although the size is not critical. Theinner cylinder 36 rotates relative to the outer cylinder 38 and includesan aperture 42 of comparable width. The unapertured portion of thecylinder 38 is arranged to occlude and mask the aperture 40. By suitablerotation of the control knob 24 of FIG. 1, the inner cylinder aperture42 is rotated, providing an adjustable slit which ranges from fullyclosed to fully opened. In operation, the setting is determined by theintensity of the radiation source 34, and by the relative lateral speedof the films through the preprocessor 10.

The negative film 18 traverses a similar path. After entering at theaperture 20, the path includes the first station and the radioactiveionizers 26' and the opposed brush pairs 28' at the second station. Thenegative film '18 is arranged to pass below (as seen in FIG. 2) the drum32, and is not subjected to any actinic radiation therefrom. Since thehigh speed fluid flow transverse to the direction of film travel,extends through the entire preprocessor 10, a flow through andpreexposer drum 32 in the axial direction keeps the drum and theradiation source sufiiciently cool so as not to adversely affect thenegative film 18.

Turning next to FIG. 3, there is shown, in somewhat greater detail, apreexposer drum 32 suitable for use in the present invention. As shown,the drum 32 includes an outer cylinder 38 and an inner cylinder 36.Concentric with the inner cylinder 36 and rotatable therewith is areflector member 44 which is substantially cylindrical I and which hasan aperture 46 that is at least coextensive with the wide aperture 42 ofthe inner cylinder 36.

The radiation source 34 is shown eccentrically mounted with respect tothe drum 32, but its location is primarily a matter of design choice.The outer cylinder 38 is anchored to the frame of the preprocessor 10and the inner cylinder 36 which is rotatably supported by the outercylinder 38, is connected to the control knob 24 and is rotated by theknob. By appropriate adjustment of the control knob 24, the aperture 42of the inner cylinder 36 can coincide with as much or as little of theaperture 40 of the outer cylinder 38 as is required, thereby providingan adjustable width slit for the correct preexposure of the positivefilm stock 12.

In FIG. 4, there is shown, diagrammatically one surface of the negativefilm 18 as it traverses the negative film path. The locations of theionizers 26', the brush pairs 28' and the airflow path relative theretoare all indicated in FIG. 4. It will be clear that if a suflicientvolume of air is moved at a high velocity, all contaminants releasedfrom the surface of the film can be completely removed from the vicinityof the film surface.

Within the art of winding and reeling, it may be desirable to process aweb entirely within a liquid fluid medium. In such applications, itstill may be appropriate to provide opposed brushes to clean the surfaceof the web and to provide a high velocity flow of fluid transverse tothe direction of web travel for removing contaminants from the vicinityof the Web. Accordingly, the present invention need not be limited tofilm preprocessors but may have more general utilization in the art ofwinding and reeling and in the cleaning of continuous webs as apreliminary step in a fabrication process.

What I claim as new is:

1. In conjunction with an extended web, a web surface cleaner adaptedfor relative motion with respect to the web in the direction of webextension, comprising in combination:

(a) shroud means tending to enclose the web and having a longitudinalopening substantially parallel to the web;

(b) cleaning means connected to said shroud means and positioned in thepath of relative motion, for removing contaminants from the web surface;

(c) removal means including differential fluid pressure means arrangedto provide a fluid pressure difference transverse to the path ofrelative motion and across the surface of the web, whereby a high volumefluid flow traverses the web surface and said cleaning means forsweeping contaminants therefrom; and

(d) preexposing means in the path of relative motion, said preexposingmeans being positioned to be cooled by the fluid flow.

2. Apparatus of claim 1 wherein said cleaning means include a pair ofopposed brushes at a first station positioned to contact opposite websurfaces and opposed radioactive sources positioned adjacent oppositeweb surfaces, and said removal means are adapted to be connected to ahigh volume, vacuum source, said fluid being air, the air flowmaintaining said brushes in an agitated state.

3. A film preprocessor for cleaning the surfaces of positive andnegative film stock prior to their application to a utilization devicecomprising in combination:

(l) shroud means for substantially enclosing the preprocessor, saidshroud having openings extending in the direction of film travel;

(2) cleaning means positioned adjacent the film surfaces for removingcontaminants therefrom;

(3) sweeping means including differential fluid pressure means forproviding a high volume fluid flow through said shroud openingsin adirection trans verse to the direction of film travel for transferringcontaminants from the vicinity of the film surfaces and for removingcontaminants from said cleaning; means; and

(4) preexposing means in the path of film travel said preexposing meansbeing positioned to be cooled by fluid flow.

4. Apparatus of claim 3 wherein said sweeping means are adapted to beconnected to a high volume, vacuum source, said fluid being air and saidcleaning means include at a first station adjacent the path of filmtravel, first and second opposed brush pairs respectively contacting thepositive and negative film said brush pairs being positioned to beagitated and cleaned by said air flow, and said cleaning means furtherinclude at a second station adjacent the path of film travel first andsecond opposed pairs of radioactive sources for applying anelectrostatic charge to the surfaces of the positive and negative films,respectively.

References Cited UNITED STATES PATENTS 6/1956 Walkup et al. 151.5 4/1964Hanscom et al 15-100 NORTON ANSHER, Primary Examiner D. I. CLEMENT,Assistant Examiner

